LCGB Forums

Yes it makes sense. Without a gear engaged there is enough friction still in the clutch to spin the cluster and all the gears. Try pushing the bike in neutral, or lifting the back wheel off the ground and spinning it to rule out the gear selector first.

Sticky wrote:Yes it makes sense. Without a gear engaged there is enough friction still in the clutch to spin the cluster and all the gears. Try pushing the bike in neutral, or lifting the back wheel off the ground and spinning it to rule out the gear selector first.

LATEST
Tried pushing bike in Neutral - no noise
OK so this time I used tippex on any suspect area of inner casing and kickstart shaft to check for any rubbing when removed, also remove kickstart piston to eliminate potential of rubbing on first gear and refitted casing etc - bump started ---- same noise EXCEPT for when in gear and clutch pulled IN as previous! - let clutch out and noise returns , place in neutral noise is there irrespective of clutch pulled or not.........

No rubbing on any inside areas of casing

Suggestions please??? - we will get there..........................

If you can Jack the back end and pull the clutch in.
If you have any drag the wheel will slowly rotate.
It's common to have some drag when the oil is cold.
You might notice a clunk when you select first the first time you set off.

NO MORE IDEAS THEN ???? i have a video with the noise but file too big for here

I have had exactly the same problem on an LI125S I have rebuilt on first startup it is quiet , but after a minute or two if starts to rattle. And like you clutch in select gear and it stops. I was really hoping someone would have the answer!

Warkton Tornado No.1 wrote:If the noise disappears with clutch pulled in & gears engaged, then the problem is most likely within the gearbox area.

My suspicions would be:

something is catching on the first gear or the inner clutch top plate (typically the kickstart) or;

the gears are noisy through too much clearance, a mismatch of gears or a broken tooth/teeth.

Strip down seems inevitable & I would suggest that you have a new, really thick chain case gasket & a selection of gearbox shims to hand as that may be all that it takes to cure it.

Sorry if I've missed it, but I can't find any mention of you having checked that the inner clutch top plate (pressure plate) or any part of the clutch is rubbing on the kickstart. Ideally, the pressure plate should look like new, not like an old 45 RPM record.

If it isn't that & you have the correct shimming to give as close to 0.003" as is possible, & the gears are not missing any teeth, then you should check the only things likely I believe to be remaining, which are mismatched gears (Sticky's book has number of teeth & outside diameter), a bad endplate bearing/journal/lay-shaft journal or the cursor itself.

Warkton Tornado No.1 wrote:

Warkton Tornado No.1 wrote:If the noise disappears with clutch pulled in & gears engaged, then the problem is most likely within the gearbox area.

My suspicions would be:

something is catching on the first gear or the inner clutch top plate (typically the kickstart) or;

the gears are noisy through too much clearance, a mismatch of gears or a broken tooth/teeth.

Strip down seems inevitable & I would suggest that you have a new, really thick chain case gasket & a selection of gearbox shims to hand as that may be all that it takes to cure it.

Sorry if I've missed it, but I can't find any mention of you having checked that the inner clutch top plate (pressure plate) or any part of the clutch is rubbing on the kickstart. Ideally, the pressure plate should look like new, not like an old 45 RPM record.

If it isn't that & you have the correct shimming to give as close to 0.003" as is possible, & the gears are not missing any teeth, then you should check the only things likely I believe to be remaining, which are mismatched gears (Sticky's book has number of teeth & outside diameter), a bad endplate bearing/journal/lay-shaft journal or the cursor itself.

OK stripped the clutch and gearbox out - able to check endplate clearance much better when clutch out of the way and it seems good at less than 0.003, one thing i did notice is that there was some evidence of rubbing on casing under the gearcluster (yes there is a washer but I wonder if its too thin?) - looked on scootopia and only one type available but no thickness dimensions given - mine is 0.8 so I tried the shim which is almost same dia but 1.2 mm thick and there is no rubbing on casing - has this been the problem I wonder?? - SHIMS/washer mixed up or just co-incidence???
Can anybody tell me the thickness of the Cluster Thrust washer please??

1mm thick, I think

The shim at the bottom of the cluster is one size only.When you tighten the centre clutch nut it should pull the cluster up away from the case.As far as I can see the shim at the bottom of the cluster is only there to stop the bearing from touching the cluster

HxPaul wrote:The shim at the bottom of the cluster is one size only.When you tighten the centre clutch nut it should pull the cluster up away from the case.As far as I can see the shim at the bottom of the cluster is only there to stop the bearing from touching the cluster

its deffo been touching at there are visible witness marks - my shim is 0.8mm

al pushpak wrote:1mm thick, I think

sorry need an accurate dimension - mine is 0.8mm the extra 0.2 could make all the difference if correct

Gear cluster shim is supposed to be 1.0mm

Have you got a manual by "sticky".If not its the best £25 you will ever spend on a Lambretta.I use a second edition of "sticky's"manual and the picture of the shim is on page 91.

HxPaul wrote:Have you got a manual by "sticky".If not its the best £25 you will ever spend on a Lambretta.I use a second edition of "sticky's"manual and the picture of the shim is on page 91.

Yes I have one and my shim looks the same but no thickness given !

The shim thickness isnt needed because there is only one.If you need a different thickness of shim,then there is something seriously wrong somewhere.
There is a post here that might have something relevant to your position. viewtopic.php?f=10&t=10011&p=89789#p89789

HxPaul wrote:The shim at the bottom of the cluster is one size only.When you tighten the centre clutch nut it should pull the cluster up away from the case.As far as I can see the shim at the bottom of the cluster is only there to stop the bearing from touching the cluster

The shim is purely to prevent premature wear of the bearing cage on the face of cluster & can be left out in certain circumstances, such as when there is weld preventing it's use. (Homemade close ratio clusters were often made by grafting on the fourth gear of one cluster onto the first three of another)

HxPaul wrote:The shim thickness isnt needed because there is only one.If you need a different thickness of shim,then there is something seriously wrong somewhere.
There is a post here that might have something relevant to your position. viewtopic.php?f=10&t=10011&p=89789#p89789

Nothing short of stripping out the gearbox & thoroughly checking the contents will sort this problem, IMHO

harps2 wrote:

HxPaul wrote:Have you got a manual by "sticky".If not its the best £25 you will ever spend on a Lambretta.I use a second edition of "sticky's"manual and the picture of the shim is on page 91.

Yes I have one and my shim looks the same but no thickness given !

Beg to differ

whooops never saw that - thanks

Well finally put her all back together with new shims, checked all gears for any wear/damage everywhere and managed to increase size of gearbox shim to reduce clearance - Guess what ---....




STILL THE BLOODY SAME !11

the noise only goes away when you PULL CLUTCH INN AND SELECT GEAR - let clutch out and noise returns.................................

Chain alignment??